This European Standard specifies requirements for moisture penetration and the long term test method for insulating glass units and ensures by means of an adequate evaluation of conformity to this standard that over time: -- energy savings are made because the U-value and solar factor do not change significantly; -- health is preserved because sound reduction and vision do not change significantly; -- safety is provided because mechanical resistance does not change significantly. It covers additional characteristics that are of importance for trade. Marking conditions are included. For glass products with electrical wiring or connections for e.g. alarm or heating purposes, this standard covers only wiring subject for electrical potential difference to earth less than 50 V a.c. or less than 75 V d.c. The main intended uses of the insulating glass units are installations in buildings and constructions such as in windows, doors, curtain walling, roofs and partitions where there exists protection against direct ultraviolet radiation at the edges. NOTE 1 In cases where there is no protection against direct ultraviolet radiation at the edges, such as structural sealant glazing systems, additional European technical specifications should be followed. NOTE 2 Units where the nature is only artistic are not part of this standard. This Part of this standard, which is inextricably bound up with the other Parts of this standard, covers the moisture penetration by testing as one means of verifying whether a product made in accordance with its system description conforms with the relevant aspect of the definition on insulating glass units.